flavonolen

Flavonols, sometimes referred to as flavonolen in some languages, are a major subclass of flavonoids, a broad family of polyphenolic compounds produced by plants. They share a 3-hydroxyflavone backbone and commonly occur as glycosides. The best-known flavonols are quercetin, kaempferol, and myricetin, which accumulate in a wide range of fruits, vegetables, grains, herbs, and beverages, contributing to color, flavor, and plant defense.

Dietary sources of flavonols include onions, apples, berries, grapes and wine, tea, kale, and broccoli. In foods, flavonols often occur as aglycones or as sugar-attached glycosides. Their levels in foods can be influenced by cultivar, ripeness, processing, and storage.

Biosynthesis and metabolism start with the phenylpropanoid pathway in plants, leading to dihydroflavonols and, through the action of flavonol synthase, to flavonols. In humans, flavonols are absorbed to varying degrees, frequently after deglycosylation. Once absorbed, they are mainly conjugated (e.g., glucuronidation, sulfation) in the intestinal wall and liver and then distributed, metabolized, and excreted via urine or bile. Bioavailability is influenced by food matrix, gut microbiota, and individual metabolism.

Health effects associated with flavonols have been studied extensively. In vitro and animal studies show antioxidant, anti-inflammatory, and potential anti-cancer properties; human studies yield mixed and often inconclusive results regarding cardiovascular risk reduction or cancer prevention. There is no established daily intake recommendation, and dietary intake from a varied diet is generally considered safe. Supplements are not universally recommended due to variable bioavailability and potential drug interactions.